In the world of Black newspapers, that name alone was enough to attract readers.

Charles H. Loeb was a Black war correspondent whose articles in World War II were distributed to papers across the United States by the National Negro Publishers Association. In the article, Mr. Loeb told how bursts of deadly radiation had sickened and killed the city’s residents. His perspective, while coolly analytic, cast light on a major wartime cover up.

The Page 1 article contradicted the War Department, the Manhattan Project, and The New York Times and its star reporter, William L. Laurence, on what had become a bitter dispute between the victor and the vanquished. Japan insisted that the bomb’s invisible rays at Hiroshima and Nagasaki had led to waves of sudden death and lingering illness. Emphatically, the United States denied that charge.

But science and history would prove Mr. Loeb right. His reporting not only challenged the official government line but also echoed the skepticism of many Black Americans, who, scholars say, worried that race had played a role in the United States’ decision to drop the experimental weapons on Japan. Black clergy and activists at times sympathized openly with the bomb’s victims.

“They were willing to question the main narrative,” said Alex Wellerstein, a historian who glimpsed this skepticism while researching his recent book, “Restricted Data: The History of Nuclear Secrecy in the United States.”

Mr. Loeb’s questioning never got the recognition it deserved. While hailed as a civic leader in Cleveland, his hometown, and more widely as a pioneering Black journalist, he was unappreciated for having exposed the bomb’s stealthy dangers at the dawn of the atomic age. His insights, until now, were lost to history.

Mr. Loeb’s own newspaper, The Cleveland Call and Post, gave him a banner headline on Sept. 8, 1945, when he witnessed Japan’s formal surrender on the U.S.S. Missouri.

The Radiation Lies

In his article, Mr. Loeb told of a press tour of Hiroshima that had crossed paths with a military investigation of the atomic victims by American scientists and doctors. The study had been ordered by Maj. Gen. Leslie R. Groves of the U.S. Army, who directed the making of the bomb, and led by his deputy, Brig. Gen. Thomas F. Farrell. One scientist was surprised to hear General Farrell tell the investigative team in an early briefing that its mission was to “prove there was no radioactivity.”

General Groves, historians say, wanted the bomb to be seen as a deadly form of traditional warfare rather than a new, inhumane type. An international treaty in 1925 had banned the use of germ and chemical weapons. The head of the Manhattan Project wanted no depiction of atom bombs as uniquely terrible, no public discussion of what became known as radiological warfare.

Historians say General Groves understood the radiation issue as early as 1943 but kept it so compartmentalized that it was poorly known by top American officials, including Harry S. Truman. At the time he authorized the Hiroshima bombing, President Truman, scholars say, knew almost nothing of the bomb’s radiation effects. Later, he spoke of regrets.

Shortly after the atomic strike of Aug. 6, 1945, The Times began covering the radiation dispute between Japan and the United States. In September, the headline of Mr. Laurence’s Page 1 article said scientific readings at the American test site “Confirm That Blast, and not Radiation, Took Toll,” contradicting “Tokyo Tales” of ray victims. The next day, The Times ran an article with a Toyko dateline in which General Farrell’s investigative team, as the headline stated, found “No Radioactivity in Hiroshima Ruin.”

General Groves and his aides, it turns out, were telling only half the story, as Mr. Loeb came to detail in his reporting.

Exploding atom bombs emit two kinds of radiation. In the first seconds, the expanding fireball sends out colossal bursts of neutrons and gamma rays powerful enough to speed through the air for miles and still penetrate steel, concrete and human bodies. They break chromosomes and upend the body’s cellular machinery, causing sickness, cancer and death. These disrupters vanish instantly and are hard to measure directly.

Atomic detonations also generate a second, more persistent and detectable wave. The split atoms of nuclear fuel produce hundreds of different kinds of radioactive fragments, including Strontium-90 and Cesium-137. They can emit their own deadly rays for years. The particles ride the churning mushroom cloud into the sky, travel on the wind for hundreds of miles, and rain back to earth as radioactive fallout. Detecting them is easy. The clicking sounds of Geiger counters reveal the radiating particles.

At Hiroshima, the American scientists did find detectable fallout — but not at ground zero. Downwind, they found it had produced a minor trail of weak radioactivity that led to the city’s edge and a dense bamboo forest.

Even so, General Groves and his aides, during press tours in New Mexico and Japan of the atomic detonation points, directed attention to the low readings of Geiger counters as evidence of little or no radiation danger.

“You could live there forever,” Mr. Laurence of The Times quoted the general as saying of Hiroshima.

In contrast, Mr. Loeb addressed the fireball’s initial burst, not the nonexistent fallout at ground zero. He did so by reporting on the findings of Col. Stafford L. Warren, who before the war was a professor of radiology at the University of Rochester.

James L. Nolan Jr., author of “Atomic Doctors,” said Colonel Warren was careful in his medical reports to downplay the ills. “Groves was his boss,” Mr. Nolan said in an interview. “He knew his audience.” The subtitle of Mr. Nolan’s book is “Conscience and Complicity.”

Mr. Loeb’s education most likely helped him discern the truth. At Howard University, one of the nation’s leading historically Black colleges and universities, he had taken a pre-med curriculum before turning to newspaper work and was familiar with the basics of physics and chemistry, anatomy and pathology, X-rays and lead shielding. What kept him from going to medical school, he recalled late in life, was lack of tuition, not interest.

It’s unclear where Mr. Loeb encountered Colonel Warren. It could have been at a news conference, a social occasion or both. In Tokyo, both men frequented the Dai-ichi Hotel, which was a billet for military officers and civilian correspondents.

That October, Mr. Loeb’s article was carried by The Atlanta Daily World as well as other Black-owned newspapers such as The Baltimore Afro-American, The Philadelphia Tribune and The Cleveland Call and Post, where he had worked before the war and later returned. The papers were part of a Black press group that had been founded early in the war by 22 publishers and saw large spikes in circulation as Black readers sought to learn about their soldiers.

Mr. Loeb described the correspondents returning from Hiroshima as “completely flabbergasted.” In contrast, his own article was unemotional. He numbered his conclusions, as if writing a scientific paper. Radiation was his third point, after blast and damage.

First, Mr. Loeb introduced “Our Colonel Stafford Warren” — his use of the possessive pronoun evoking a sense of trust — as the bomb project’s “Chief Medical Officer.” The journalist said nothing of Colonel Warren’s denying the existence of radiation victims — the ostensible marching orders of the investigative team. Instead, he quoted the colonel as identifying the proximate cause of the gruesome ills.

Colonel Warren, the radiologist, Mr. Loeb said, judged that “a single exposure to a dose of gamma radiation (similar in effect to X-rays) at the time of the detonation” gave rise to the gruesome ills. His proposed cause was understated and almost clinical in nature but a radical departure from the blanket denials. Mr. Loeb, in closing the section, noted that Colonel Warren ruled out the possibility of sickness caused by “dangerous amounts of radio activity on the ground.”

Military censorship took out any attempt by reporters back then to portray human suffering. It allowed depictions of broken buildings, not broken bodies. Mr. Loeb’s article thus gave no details of the atomic victims.

But memories of Japan haunted him long after the war, according to his daughter Stella Loeb-Munson. She recalled him talking of melted faces, of skin hanging from wasted bodies. During an interview, Mrs. Loeb-Munson pointed to a photograph he took of a crumpled body on a sidewalk.

“It totally messed him up for years,” she said. Slowly he turned from sullen to angry. “He had to talk about it — he had to,” Mrs. Loeb-Munson said. “He was really messed up. He never really got over it.”

The Radiation Victims

A search of databases suggests that few if any journalists of Mr. Loeb’s day approached his level of detail and tight focus in telling of the radiation poisoning.

The Times sought to ignore the topic altogether. Beverly Deepe Keever, a professor of journalism, analyzed its coverage of the Hiroshima bombing and reported that out of 132 articles she examined, she could find only one that mentioned radiation.

Even so, by November 1945, a month after Mr. Loeb’s article, public awareness of the radiation issue had grown to the point that General Groves could no longer deny the toll of the bomb’s initial bursts. Instead, he described their impact on humans as “a very pleasant way to die.”

The Black press in subsequent months kept pounding away. The Baltimore Afro-American spoke of “thousands of radiation victims.”

The military itself soon cast light on the enormity of the misinformation campaign. In June 1946, the United States Strategic Bombing Survey said most medical investigators saw the radiation emissions at Hiroshima and Nagasaki as responsible for up to 20 percent of the deaths. If the bombings took roughly 100,000 to 200,000 lives — today considered a credible range — the radiation killed up to 40,000 people.

The rays also produced a dark legacy. Over decades, studies of the survivors revealed that they endured high rates of cancer, stroke, cataracts and heart disease. Babies in utero at the time of the bombings suffered poor development, epileptic seizures and reduced head size.

Mr. Loeb died in 1978 at 73. While getting no credit for his atomic scoop, he became known late in life among other journalists as the dean of Black newsmen. In 1971, he spoke of his long career in an oral history interview with Columbia University. Then 66 and managing editor of The Cleveland Call and Post, Mr. Loeb said that he regretted not going back to medical school but that he felt he probably did more social good as a journalist than he would have as a surgeon.

His great good fortune, he added, was marrying a woman who put personal goals ahead of money. “We’ll starve together,” he recalled his wife, Beulah Loeb, saying.

Mr. Loeb said nothing of his radiation article or what he had witnessed at Hiroshima but spoke at length about Black publishing and the community it served.

“One of our functions is to tell the Black side of any story,” he said, as Black readers were often skeptical of the white news media. Even when Black papers got scooped on big stories, he added, “our readers still buy our newspapers to see what we said about it.”

Black newspapers perform “a real service” not only for Black people but also, Mr. Loeb said, the press in general because they reliably present alternative points of view and fresh perspectives.

“You have to tell the truth,” he added. If not, he said, “you’re in trouble.”